At first , Mention whether your phone is android, windows or iphone.
If its android then root it and then download RAM EXPANDER or RAM MANAGER from playstore .
Both these app will use your SD card as an additional memory to provide as RAM for your device.
It will do the trick.
And for your PC , Use a pendrive and it will work as extra memory or RAM for your computer.
this link will help... -> http://www.wikihow.com/Use-Pen-Drive-As-RAM